Among Republicans, calling Obama “worse than Carter” is now as cliched as praising Reagan or standing in front of a bunch of American flags.

But here’s the problem: More and more people have no idea who Republicans are talking about, so this barb has less sting than Republicans think.

According to 2010 Census data, 126 million Americans were born after Carter left office — about 41 percent of the entire U.S. population.

And as of this Monday, it’s been exactly 33 years since Carter’s last day as president. To put it another way, the Carter presidency is now as distant from us as Truman’s 1948 re-election was from his last day in office.

Besides, from a historical perspective, Carter isn’t necessarily the worst president — or even the worst Democratic president.

Surveys by historians tend to give Carter poor marks, placing him in the company of such lesser colleagues as Chester Arthur and Rutherford B. Hayes, but still above the worst, such as James Buchanan, who dithered in the days leading up to the Civil War, or Warren G. Harding, who was beset by scandal.